Field of the Invention
The invention relates to a method for dressing a honing tool which is intended for the fine machining of the teeth of a toothed wheel. For the dressing processing operation, there is used a dressing wheel which, during the dressing operation with the honing tool which is intended to be dressed, continuously rolls at an axial intersection angle so that teeth which are formed on the dressing wheel move into engagement with teeth which are formed on the honing tool and which each have an upper face which is intended to be dressed and tooth flanks which are also intended to be dressed.
Description of Related Art
The honing of toothings or toothed wheels is a fine machining method involving cutting using a geometrically non-defined blade in order to process toothed wheels. In this instance, hardened toothed wheels are generally honed using a honing tool which is also referred to as a honing wheel, honing ring or honing stone. The honing tool comprises, for example, a synthetic resin or ceramic bond in which hard material grinding grains of white corundum, sintered corundum or boron nitride are embedded.
As a result of the continuously operating toothed wheel honing method, it is possible above all to correct short-wave toothing deviations. These may lead to noises which are very unpleasant for the human ear. As a result of their high-frequency nature, they may further have a negative effect on the service-life of the respective component.
During the honing processing operation which is carried out continuously, the toothed-wheel-like honing tool and the toothed wheel which is intended to be processed roll on each other in a synchronous rotation. The toothing of the honing tool and toothed wheel mesh in this instance at an axial intersection angle which is adjusted between the skewed rotation axes of the honing tool and toothed wheel.
As a result of the rolling rotation and the axial intersection angle, there is between the tooth flanks of the honing tool and the tooth flanks of the toothed wheel which is intended to be processed during rolling contact a sliding relative movement which brings about the chip removal on the toothed wheel. The sliding movement of the honing tool in contact with a tooth flank of the toothed wheel is composed of a radial movement which is produced by the rolling rotation and an axial movement which is produced by the axial intersection angle. The axial and radial components of the sliding movement result in the processing marks which are characteristic of toothed wheel honing and which can be seen as “herringbone patterns” on the tooth flanks of the toothed wheel which has been completely processed.
As a result of the toothed wheel honing operation, it is particularly possible to positively influence the noise behaviour and the load-bearing capacity of a toothing as a result of the correction of short-wave toothing deviations and the introduction of residual compressive stresses in the region of the toothed wheel edge zone.
The honing tool is dressed before the first use in the new state and after a specific period of use. The dressing operation serves to correct production-related or wear-related shape deviations of the honing tool from the optimum desired shaping in each case and thus to sharpen the respective tool with respect to the geometry thereof.
In particular with internally toothed honing tools, so-called honing rings, the dressing is generally carried out in two steps. In a first step, the outside or internal diameter of the honing ring is dressed using a generally cylindrical dressing roller. In a second step, the tooth flanks of the honing ring are then dressed using a toothed dressing wheel.
The result of this operating method is that the dressed upper surfaces and a respective dressed tooth flank of a tooth of the honing ring converge in the region of the tooth tip in a sharp-edged upper corner. The path described by this upper corner during the honing operation changes over the useful length of the honing tool. In the new state, as a result of the sharp-edged upper corner on the toothed wheel workpiece in the tooth base region, there is produced a sharp notch which reduces the tooth base load-bearing capacity or tooth base strength of the toothing of the toothed wheel. This effect decreases as the useful length of the honing tool decreases, that is to say, as the wear or repeated dressing operations increase. As a result of wear and repeated dressing, with honing tools which are constructed, for example, as a honing ring, the radius of the base rounding which is produced is increased.
For the honing processing of toothed wheels for which fine machining of the tooth base region is also required, there is therefore artificially produced a state of the honing tool which would be produced during use only after a specific period of use or after a specific number of dressing operations. The effective period of time for which the honing tool can be used is thereby significantly shortened compared with the useful period for which the honing tool would actually be able to be used starting from the new state. The artificial shortening of the service-life naturally leads to increased tool costs.
Modern gear mechanism constructions increasingly demand, that during the honing processing operation of toothed wheels, the tooth base region is also honed in order to also achieve optimum load-bearing capacities in the tooth base region by means of optimisation of the surface state. In this instance, it is desirable to prevent steps in the surface nature or the geometry in the region of the transition between the respective tooth flank and the adjacent tooth base region.